The plane, a Soviet-made twin-propeller Antonov-24, went down in remote, thickly forested terrain, leaving a column of smoke pouring from the crash site and no signs of survivors, according to state media and videos published by investigators.

The Angara Airlines flight was headed to the town of Tynda from the city of Blagoveshchensk when it disappeared from radar at around 1:00 pm local time (0400 GMT).

A rescue helicopter later spotted the burning fuselage of the plane on a forested mountain slope about 15 kilometres (nine miles) south of Tynda's airport.

Videos published by Russian investigators showed smoke rising from the crash site and what appeared to be fragments of the plane strewn across the forest floor.

A search and rescue team arrived only hours after the crash at the remote, hard-to-reach site and found no evidence of survivors, according to the state news agency TASS.

Investigators did not say what caused the crash.

Weather conditions at the time of the incident were poor, Angara Airlines CEO Sergei Salamanov told Russia's REN TV channel.

"The commander made the decision to carry out the flight," he was quoted as saying.

Tynda, home to around 30,000 people, lies in an area of thick taiga forest about 200 kilometres (125 miles) from the Chinese border.

At least one Chinese national was on the flight, state media in China reported.

Chinese President Xi Jinping sent a message of condolence to Russian counterpart Vladimir Putin.

"I would like to express my deep condolences to the victims and sincere sympathy to the families of the victims," Xi said, according to Chinese state broadcaster CCTV.

The plane dropped from radar while attempting a second approach to land at Tynda, regional prosecutors said.

The forest terrain complicated search efforts, a rescuer told the TASS agency.

"The main search operations are being conducted from the air," it said.

Angara Airlines, a small regional carrier based in the Russian city of Irkutsk, did not immediately release a statement on the crash.

- Five children -

Russia's aviation watchdog has not yet given a definitive number of people on board.

The Amur region's governor, Vasily Orlov, said the plane was carrying 43 passengers and six crew members.

Among the passengers were five children, he said.

The TASS agency cited emergency services as saying the plane was carrying 40 passengers and six crew.

Aviation authorities have opened an investigation.

The plane appeared to have been manufactured almost 50 years ago, during the Soviet era, according to civil aviation database Russianplanes.net.

In 2021, the aircraft's airworthiness certificate was extended until 2036, data from the site showed.

AFP was not able to immediately verify this information.

The Antonov-24 is a popular, Soviet-designed turboprop plane that first entered into service in 1959.

Russia has taken steps to switch from Soviet aircraft to modern jets in recent years, but ageing light aircraft are still widely used in far-flung regions, with accidents frequent.